OBJECTIVE To explore whether there are socioeconomic, ethnic, and geographical inequalities in dental caries among 12-year-old Chinese children. METHODS Data from 2,307 12-year-old children living in Guangxi, Hubei, Jilin, and Shanxi and who participated in the Third National Oral Health Survey in China were used for this study. Data were collected through structured questionnaires and clinical examinations with children. The decayed, missing, and filled permanent teeth (DMFT) index and number of decayed teeth (DT) were the outcome measures for analysis. Inequalities in DMFT and DT by socioeconomic position (parental education), ethnicity, and geography (province of residence and urbanicity) were assessed in unadjusted and adjusted negative binomial regression models. RESULTS Ethnicity and geographical factors, but not parental education, were significantly associated with childhood dental caries in unadjusted models. However, only geographical factors remained significantly related to dental caries after mutual adjustments. The DMFT index and DT were higher among children living in Jilin and Guangxi than those of children living in Hubei and Shanxi, and also higher among children living in rural areas than in those living in urban areas. CONCLUSIONS This analysis shows inequalities in dental caries among 12-year-old children in four provinces of China. There were considerable inequalities in children's DMFT and number of decayed teeth by geography but not by ethnicity or parental education.